Various types of terminals having a display screen, such as mobile phones, are widely used. A number of pixels that can be displayed on a display screen at one time (hereinafter, “screen size”) varies depending on a type of a terminal. Therefore, it is necessary that a number of pixels of an image (hereinafter, “image size”) to be displayed on a display screen of a terminal be converted according to the size of the display screen used, so that a layout is correctly maintained.